The present invention is directed to a valve assembly for use in discharging a fluid from a container, such as a flexible container, and for preventing any flow of contaminants through the valve assembly into the container. The valve assembly includes an elongated valve body with an elastomeric sheath laterally enclosing the outside surface of the valve body. Flow passes through the valve body into the space between the outside surface of the valve body and the elastomeric sheath. Subsequently, the flow returns inwardly through the valve body and out through an outlet or discharge channel.
In dispensing sterile fluids from a container where the container has an extended period of use-life, it is important to prevent any back flow of contamination into the container during and after the dispensing operation has been carried out. Contamination in the form of materials originating from outside of the valve assembly and container may include microorganisms, atmospheric gases, moisture, dust and the like. If the sterile fluid is contaminated it can affect the quality, potency and even safety of the product.
If a container of a sterile fluid has a one-time use and is not intended to be dispensed over an extended period of time, the problem of contaminants flowing into the container usually does not exist. In one known liquid handling container disclosed in U.S. Pat. No. 2,715,980 to Frick, the valve mechanism involves a valve body with a central port extending through the valve body and with branch ports extending from the central port to the outside surface of the valve body. An expansible sleeve, such as a sleeve of a rubber-like material, encloses the outside surface of the valve body preventing flow from the branch ports. When a fluid is to be dispensed, it flows through the central port and then through the branch ports causing the sleeve to expand and permitting the fluid to flow out around one end of the sleeve. During such flow, it is possible for contaminants to flow into the expanded end of the sleeve and then through the branch ports and central port, back into the container. An effective blockage of contaminant flow into the container is not available.
Another valve incorporating an elastic tube or sleeve is disclosed in U.S. Pat. No. 4,346,704 to Kulle. A parenteral solution is dispensed through a central tube or channel to branch ports which deliver the fluid to the inside surface of an elastic sleeve or tube. When the fluid is pressurized it displaces the elastic tube outwardly permitting flow from the branch ports outwardly from the end of the sleeve. The Kulle device is primarily intended for a one-time use, such as in dispensing an anesthetic. There is no particular problem with a return flow of contaminants into a container because of such one-time use. The Kulle device is intended to deliver anesthetics at high flow rates and low pressures so that accurate dispensing is possible.